The present invention resides in a combination weighing machine and is concerned more particularly with a combination weighing machine having multiple bins on each scale.
In an effort to improve the accuracy and speed of combination weighing machines, the number of scales employed in a combination weighing machine is normally increased. To avoid the expense involved with the addition of more scales to a machine, memory buckets have been added to store a product previously measured by a scale, and an acceptable combination is obtained by searching combinations of the measured weights in the memory buckets. For example, U.S. Pat. Nos. 4,418,771 and 4,437,527 disclose combination weighing machines in which the product is first weighed in a scale and then discharged into memory buckets for selection of an acceptable combination. When that combination is found, the associated memory buckets are dumped into a common discharge path leading to a packaging or other machine.
Alternatively, the combination search can be performed among the weights of products in both the memory buckets and the weigh scales, as indicated in U.S. Pat. No. 4,454,924.
One disadvantage of the prior art machines which employ memory buckets is that they add another tier of buckets below the weigh scales and increase the overall height of the machine. Furthermore, the memory buckets introduce an additional step in dropping product through the machine from a bulk distributor above to the discharge path below. The additional height plus the additional handling increase the likelihood of damage to the product. The memory buckets in a combination weighing machine cannot be checked or tared like scales for product and weight buildup, and therefore the overall accuracy of the discharged weights suffers. The cost of the combination weighing machine is also increased through the additional height of the machine required by the memory buckets and the cost of the memory buckets including the dumping doors as well as the dumping controls for both the scales and the memory buckets.
It is accordingly a general object of the present invention to provide a combination weighing machine having the speed and accuracy of a combination weighing machine with a high number of scales or scales and memory buckets without the disadvantages discussed above.